The present invention relates to adjustment mechanisms suited for vehicle seats, and particularly mechanisms that include a memory feature. The inventive adjustment system is of the type that provides a means of selecting a preferred seat position, releasing the adjustment mechanism for free movement of the seat, and automatically arresting the adjustment mechanism, securing the seat at the selected position.
One typical use for this type of seat adjustment mechanism is for the front seat of a two-door passenger vehicle. In such a vehicle, the seat backs of the front seats are adjustable. By the simple expedient of a hand lever, a passenger can adjust the angle of incline of the seat back to a selected position of comfort. In many vehicles, the seat back can be adjusted from a substantially vertical orientation to a nearly horizontal, reclined position.
When passengers enter the rear seat of a two-door vehicle, it is often necessary to pivot the seat back of the front seat forward to allow easy access to the rear of the vehicle. This process is known as xe2x80x9cdumpingxe2x80x9d the front seat. In some seat designs, the dumping process occurs by manipulating the same lever that is used to adjust the incline of the seat back. This approach is simple, but it does not allow the passenger to easily restore the seat back to a selected position.
This process is shown schematically in FIGS. 2(a)-(c). Specifically, a seat assembly 10 is connected to the vehicle body by way of a support frame 11. The seat back 13 can be adjusted in either direction through a range of adjustment 20a to 20b relative to the seat bottom 12 and the support frame 11. As shown in FIG. 2(a), the passenger can adjust the seat back to a selected seat position 21, corresponding to an angle of inclination 22. However, when a passenger desires access to the rear of the vehicle, pivoting the seat forward as depicted in FIG. 2(b) dumps the seat back 13 from its selected seat position 21, to its dumped position 23.
In the case of some prior art seat adjustment mechanisms, using the recline adjustment to dump the seat does not allow the passenger to automatically return the seat back to the selected seat position 21, as shown in FIG. 2(c). As a result, more sophisticated systems have been developed.
One such system separates the seat recline feature from the dumping feature, as is described in U.S. Pat. No. 5,806,932, owned by the assignee of the present invention. Although the invention separates the dumping device from the normal adjustment device of the seat back, the two devices are interconnected in a single system so that the seat back can be dumped while retaining its selected angle of inclination. The system disclosed in the ""932 patent relies upon a master and slave seat lock and a memory latch to establish the angle of inclination of the seat back. To accommodate dumping, the memory latch is released while the master lock remains locked. A control subsystem coordinates simultaneous unlocking and relocking of the master and slave locks to set a selected seat position. When the dumping feature is activated, the control subsystem releases the memory latch and the slave lock, allowing the seat back to move freely, while the master lock remains locked, thereby retaining the selected position. When dumping is completed, the memory latch is restored to its locked position, re-establishing the seat back at its selected angle of incline.
While the adjustment mechanisms of the type shown in the ""932 patent provide significant benefits over other adjustment mechanisms, there remains a need for improvements to seat adjustment and dumping mechanisms. For instance, most prior adjustment and dumping mechanisms rely upon relatively bulky stamped metal components that can be expensive to manufacture and difficult to assemble and that must be strong enough to hold the seat back in position. There remains a need for a seat adjustment mechanism that incorporates the function of retaining a selected seat position into the adjustment mechanism and that eliminates the need for stamped or machined metal components that can be bulky, heavy, expensive, and difficult to manufacture and assemble.
Briefly describing one aspect of the invention, the seat adjustment mechanism includes a positioning member for positioning the seat back relative to the support frame, a locking mechanism for locking the positioning member in a selected position, such as those disclosed in U.S. Pat. No. 4,794,470, and an arresting mechanism for re-engaging the locking mechanism after the seat back is dumped and as the seat back is transiting the selected position.
The difficulties with prior seat adjustment mechanisms are overcome in one aspect of the current invention by the arresting mechanism. The seat back is dumped from its selected position by shifting the locking mechanism to its disengaged state, freeing the positioning member and attached seat back to move. After the seat back is dumped and as the seat back is returned to its selected position, the arresting mechanism shifts the locking mechanism to its engaged state, engaging the positioning member and securing the seat back in the selected position. Because the locking mechanism is released to dump the seat, there is no need for bulky stamped or machined components in addition to the locking mechanisms that are capable of latching and securing the seat. Instead, the arresting mechanism can be generally constructed of small plastic, lightweight, inexpensive components that release and activate the locking mechanism and retain a selected seat position.
In one embodiment the arresting mechanism includes an arresting member that is coupled to the positioning member and that has an adjustable length set to correspond to a selected position of the positioning member relative to the locking mechanism. The arresting member is set into action by the positioning member arriving at the selected position. The action of the arresting member activates the arresting mechanism and shifts the locking mechanism from its disengaged state to its engaged state.
In another embodiment, the arresting member is a flexible cable that is attached at one end to the positioning member and at the other end to another part of the arresting mechanism. The action of the positioning member arriving at the selected position pulls the flexible cable, shifting the locking mechanism to its engaged state.
In a further aspect, the arresting mechanism provides a means for adjusting and retaining a feature of the arresting member. In one embodiment the feature is an adjustable length in which the arresting mechanism includes a take-up reel with a flexible cable extending to an adjustable length. The take-up reel can include a rotating spool for winding excess length of the flexible cable, a reel locking means for selectively locking and unlocking the spool, and a spool spring for tensioning and respooling excess flexible cable length when the spool is unlocked.
In another embodiment, the arresting member is a tensioning member and the feature is an adjustable tension limit. The tensioning member can include a means for adjusting the tension on the member that is required to active the arresting mechanism. The action of the positioning member arriving at the selected position tensions the tension member to the adjusted tension, shifting the locking mechanism to its engaged state.
In one feature of the invention, the adjustment mechanism includes a dump lever for holding the locking mechanism in its disengaged state. Activating a dump control toggles the dump lever, disengaging and holding the locking mechanism. The action of the positioning member arriving at the selected position activates the arresting mechanism, toggling the dump lever again, which re-engages the locking mechanism, securing the positioning member at the selected position.
In a further aspect, the adjustment mechanism includes an adjustment control for adjusting the arresting member feature. Activating the adjustment control disengages the locking mechanism so that the arresting member feature adjusts as the seat back and the connected positioning member are moved to a new selected position. Release of the adjustment control re-engages the locking mechanism and retains the arresting member feature.
In still another aspect, the adjustment mechanism includes an arresting mechanism selectively operable in several positions. The adjustment state is selected when the adjustment control is actuated to adjust the feature of the arresting member. The memory state is selected when the adjustment control is released and it sets and retains the arresting member feature. The arresting state is selected when the dump control is actuated and released and it disengages the locking mechanism, releasing the positioning member until the positioning member again transits the selected position, re-engaging the locking mechanism and securing the positioning member.
In a further aspect, the adjustment mechanism includes a master locking mechanism having an arresting mechanism and a slave locking mechanism. The slave locking mechanism is operatively connected with a slave cable to the master locking mechanism. The slave cable synchronizes the slave locking mechanism with the master locking mechanism engagement and disengagement. The action of the arresting mechanism operates on the master locking mechanism. A second arresting mechanism is not required for the slave locking mechanism because of the action of the slave cable.
One object of the invention is to provide a seat adjustment mechanism that can adjust the angle of incline of the seat and restore the seat back to a selected position after dumping. Another object is to eliminate the need for stamped or machined metal components to dump and restore the seat back position.
One benefit is that the seat back can be adjusted and the angle of incline stored with a single lever. Another benefit is that the adjustment mechanism requires only a single activation of a dump control actuator to release the seat back for dumping and to automatically relock the seat back when restored to the selected position.
These and other objects of the present invention will become more apparent from the following description of the preferred embodiment.